The Old Town canoe with serial number 81512 is an 18 foot long, CS grade, HW (Heavy Water) model with Western red cedar planking, open spruce gunwales, birch decks, birch trim, and a keel. It was built between November, 1923 and April, 1924. The original exterior paint color was dark red. It shipped on April 25th, 1924 to Sheepshead Bay, Long Island, New York. A scan of this build record can be found by following the link at the attached thumbnail image below.
This scan was created with substantial grants from the Wooden Canoe Heritage Association (WCHA) and others as you probably know well. A description of the project to preserve these records is available at http://www.wcha.org/catalogs/old-town/records/ if you want more details. I hope that you will renew your membership to the WCHA so that services like this can continue. See http://www.wcha.org/wcha/ to learn more about the WCHA and http://www.wcha.org/join.html to join.
It is also possible that you could have another number or manufacturer if this description doesn't match your canoe. If you really have a 17 foot long canoe then let me know which digit is the least clear and I will make another search through the records. Feel free to reply here if you have any other questions.
Thanks, Benson. The owner thought this canoe was a 17-footer, though, so I'll have to check back with him to make sure he read the serial number or length correctly. I appreciate the great service, as always!